Let \({D}\)  be a representation of a group \(G\)  of degree \(n\) . A
character \(\chi \)  is a complex-valued function defined on group
\(G\) . For each \(A \in G,\)  let \(\chi (A) = Tr({D}(A)).\) 
Equivalent representations have the same character. Most remarkably,
representations which have the same character are necessarily
equivalent[1]}.
